david seckel, radio detection of astrophysical neutrinos, karlsruhe, oct. 14, 2003 radio detection...

David Seckel, Radio Detection of Astrophysical Neutrinos, Karlsruhe, Oct. 14, 2003

Radio Detection of Astrophysical Neutrinos

David Seckel

University of Delaware


Cosmic Neutrinos

• Big Bang < 1 eV Thermal• Solar .1 – 10 MeV Thermonuclear• Supernovae 5 – 50 MeV Thermal

• Atmospheric 100 MeV – 100 TeV Hadronic (-decay)• Cosmic-ray sources1 TeV – 10 EeV Hadronic• Cosmic-ray propagation 100 PeV – 10 EeV P- reactions (GZK)


Cosmic Rays

• Nuclear (P, Fe?)– ~ E-3 spectrum to 1019 eV

– Sources not observed directly

– GZK process should absorb but…

• Gamma rays– ~ E-2 ’s observed to 1012 eV

– Nearby sources only

• Suggests– E-2 source spectrum

– p,n interact in source

– Predicted fluxes


Cosmic Ray Neutrinos

production

decay

• Location– Atmosphere

– Source

– Propagation

• Flavor– No mixing

– Full mixing

• If then

Comments


Expected Fluxes

PP+X

P+

source

GZK

• Waxman - Bahcall– Known intensity

– E-2

– Thin (1 per p)

• But…– Not thin ?

– Didn’t include GZK

• Perhaps WB is better as a lower bound…Anyway - it sets the scale…


High energy cross-sections

• ~ E, E < MW2/mp

• Continued increase due to growth

of parton distribution in p,n

• The Earth becomes opaque at

high energy.

* Perhaps non-standard cross-sections – extra dimensions, black holes, etc.


Detector Scale

Atmospheric 1-100 GeV

Astro-Sources0.1 TeV - 10 PeV

GZK0.1-10 EeV


Summary of motivation

Source Status Energy Detector Scale

Technology Examples

Atmospheric Observed 1-104 GeV (40 m)3 Water Optical Cerenkov

Super-K

Astrophysical

Sources

Plausible

(but uncertain)

1 PeV 1 km3 Water Optical Cerenkov

IceCube

Antares/Nemo

GZK + “guaranteed” 0.1-10 EeV 1000 km3 Radio Cerenkov

RICE/ANITA

SALSA/GLUE

And lots of more exotic sources, cross-sections, new physics, …


Radio Detection of Showers

Askaryan: Coherent radiation

• S ~ Q ~ 0.25 Es/GeV• ~ RM ~ 10 cm• /l ~ 3 deg• Confirmed by

– SLAC T444, Saltzberg et al. PRL 2001– SLAC T460, Gorham et al. 2002


Scaling behavior

fractional excess

V t

lmax

Single particle signal

Includes LPM effect


RF spectrum

Field calculation is integral over shower profile

Separation of shower profile

Separation of form factors

With scaled frequencies

• Adapted from Alvarez, Vazquez, Zas

• “Full sim” is approx a

• Blue – Gaussian for f(z), AVZ approx c for Gy

• Red – Griessen for f(z)

Separation of phase factors


LPM effect & Hadronic showers

• LPM lengthens shower– Narrows cherenkov cone

• E < 1 EeV e CC showers y = .8• E > 1 EeV hadronic-showers – y = .2

– 3 flavors * (CC + NC) = 4.5 channels– No LPM - no 0 decay above a few PeV (coincidence).


Radio Propagation in Ice

• Rx fixed• Tx lowered into “dry” hole• t0(z) gives index of refraction• 2nd pulse is reflection


Radio Attenuation in Ice

0.1 0.2 0.5 1 2 5 10nHGHzL

0.1

1

10

100

1000l

ttaHmkL

lH- 60 CLx 100

lH- 50 CLx 10

lH- 40 CLx 1

Solid – Provorov (used by RICE)Dashed – Matsuoka + Westphal

Curves offset for visibility

RICE bandpass

• High frequency – pretty consistent• Low frequency – big variations with ice sample – proton mobility• Plans to measure at pole, 2003-04


Radio Ice Cherenkov Experiment

PI


RF Detection (RICE version)

5 km

• RF technique– Event

– Shower: EM and/or hadronic

– RF pulse

– Propagation

– Antenna

– DAQ


• 16 Rx (10 cm dipole)• 5 Tx• 3 Horns• 4 Oscilliscopes (x4) • DAQ• PCs• Pulse Generator• Dry hole

Pole:

• Network analyzer• Antenna range

Kansas:

RICE Deployment


Channel and DAQ configuration

Power

Scope

Trigger generator

Antenna

Amp in PV

cableAmpFilter

Splitter

PC• 4 hits within 1200 ns • Latch scope• TDC times to PC • On-line veto (TDC times)

• Read scope• Write to disk

• 8 sec• 1 ns sample• 500 MHz


Single Channel Calibrations

200-500 MHz: +/- 3 dB (E)

TX….RX • antenna + amplifier calibrations• cable (TX, RX) and filter• relative geometry of TX/RX (r,


Pulse shape simulation

Disc. threshold

Background taken from data sample


Limited by attenuation

60,000 e- showers at E = 1 EeVBlack dots – sampleRed dots – events which would trigger RICE

~ 5% efficiency

Limited by Cherenkov angle

Monte Carlo


1. 2. 3. 4. 5. 6.Log@EsDHPeVL- 3.

- 2.

- 1.

0.

1.

2.

goL@V ffeDHmk3 L

RICE effective volume for e-, showers

Range due to varyingsignal strength by 0.5-2

Range due to varyingattenuation by 0.5-2

Mul

tipl

y by

2

sr

This is appropriatefor e chargedcurrent events.


1. 2. 3. 4. 5. 6.Log@EsDHPeVL- 3.

- 2.

- 1.

0.

1.

2.

goL@V ffeDHmk3 L

LPM and hadronic showers

With LPMWithout LPM

“Hadronic”Es = 20% E


RICE I: Data Analysis

333.3 hrs livetime

TDC times

Waveform

data {


No Events! (yet)

ICRC 2003

SPIE 2002Astro-ph 2002

AstroPart Phys.2003


Potential Systematic Effects (see astro-ph/0206371)


ANITA

Peter Gorham


Antarctic Impulsive Transient Antenna (ANITA)

• ANITA Goal: Pathfinding mission for balloone-borne neutrino telescope

• NASA SR&T start 2003, LDB launch in `06-`07 austral summer season

• Requires early measurements of Antarctic EMI at float altitudes determines instrument final design

M. R

osen, Univ. of

Haw

aii

ANITAGondola &

Payload

Antenna array

Crush pad/struts not shown

Solar Panels

Mean ice depth ~1.2km

SIP & SIP PV array


Critical Developments

• Broad band antennas with 30 deg field of view, two polarizations

• Survey of EMI backgrounds – ANITA Lite

• Low power multichannel digitizer

– >= 1GHz analog input bandwidth (200-1200MHz)– multi-GSa/s sampling rate (Nyquist limit ideal)– minimum phase distortion for clean polarization – dynamic range (>= 10 bits)– internal Analog to Digital Conversion (ADC)– short record length (100-200ns if optimally matched)

– self-triggering with fine threshold adjustment– bi-polar triggering– deadtimeless conclude multi-hit buffering needed


32x256 SCA bank

DACs ADC

Trigger

scalers

STRAW2 Chip

16 Channels of256 deep SCA buckets

Self-Triggered Recorder Analog Waveform (STRAW)

Optimized for RF inputMicrostrip 50

Record length:128-256ns

Self-Triggering:

Target input Bandwidth:>700MHz

-LL and HL (adj.) for each channel

Sampling Rate:1-2GSa/s (adj.)

-Multiplicity trigger for LL hits

On-chip ADC:12-bit, >2MSPS

External option:MUXed Analog out

Sampling Rates>~8GSa/s possiblew/ 0.25m process

8192 analog storage cells

Die:~2.5mm2

(From Gary Varner, UH)


ANITA MC

• Ec = 3e18 eV

• 5.6 deg upcoming

• 100m depth

• Ec = 2.5e18 eV,

• 0.7 deg upcoming

• depth 950m

~30 deg

~45 deg

• Method: monte carlo ray bundles from ZHS distribution, then ray-trace through the ice+firn to surface, then use fresnel equations

• Also extending RICE Monte Carlo

• Issue: Roughness of Air-Ice interface


Current best sensitivity estimates

From: Peter Gorham


Anita-lite Configuration (w/TIGER)

• 2 quad-ridged horn antennas on SIP level

• Electronics 1atm case (also SIP level)

• PV array addition

• Telemetry integrated w/ TIGER

marriage made in heaven (Lady & the tiger)

Anita-lite PV array:Probably integrated in single

tier


ANITA-lite as-built Configuration

Antenna arrangement

Instrument housing under TIGER

Redundant fast-recovery USB harddrive (8GB)Housing, hard drive, veto antenna

Electronics integration into pressure housing


Air Shower Detection

• Demonstration that Radio Cerenkov works “in the wild”

• Detector Calibration

• Cosmic ray composition ?


Impact of shower core


RF pulse: rant= (0,0,-150m), dsh= +x on cone

Arrival time distribution

RF Pulse at antenna Combined spectra w/phases

Individual spectra above 300 GeV


Different pulse shapes for different observers


Compare strength of air/ice shower signals

-4 -2 0 2 4tns-0.00002

0

0.00002

0.00004

0.00006

EVmmc

PeV ice shower x .01redvs PeV Air shower black • Need to correct for constant n = 1.78

– Narrower C-cone

– Increases E

– No focusing

• Vertical shower– Slant will evolve shower

• Higher E more efficient– Will penetrate (less evolved)

• Proton vs Fe– Fe more evolved - larger H


Plausible event rates

• A = 1 km2

• Impact Rates– Es > 1 PeV = 108/yr

– Es > 1 EeV = 102/yr

• Threshold– E (in ice) ~ 300 PeV (RICE)

– E (in ice) ~ 10 PeV (Optimized ?)

• Need MC of air shower rates, array design– Toy calc with RICE

• 10 EeV air shower, r = 2 km, z < 45

• 0.1 EeV ice shower, z = 1 m (w/LPM)

• No ray tracing (change geometry/strength)

• eff ) = 1.9 km2sr


Composition with radio ?

Proton gammaFe

Average of 50 x 1 PeV showers


Summary

• Cosmic Rays & Neutrinos linkedOther cosmic neutrinos/particle physics not discusse

• RF detection offers large effective volumes

• RICE maturing as a prototype

• ANITA discovery potential designed for GZK

• Air shower detection w/composition ?

david seckel, radio detection of astrophysical neutrinos, karlsruhe, oct. 14, 2003 radio detection...

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